The present invention relates to detecting circuit and a related detecting method, and more particularly to a detecting circuit applied for generating a detection signal according to an input signal pair to notify a receiving system, and a detecting method thereof.
In a signal transmission system, a receiver of the signal transmission system is set to go into a sleep mode when the receiver does not receive any signal for a certain period of time, in order to reduce the current consumption of the receiver. However, the receiver should awake as soon as possible when a real signal (e.g. data signal) is transmitted to the receiver such that the receiver does not miss the inputted signal. Therefore, a signal detection circuit is installed in front of the receiver to detect if the real signal is inputted into the receiver when the receiver is in the sleep mode. When the signal detection circuit detects that the real signal has appeared on the cable connected to the receiver, the signal detection circuit awakes the receiver from the sleep mode. Then, a clock data recovery circuit in the receiver starts to lock the inputted signal. In certain advanced signal transmission systems, such as a high speed serial link system, the frequency of the inputted signal has become much faster in order to increase the data transmission rate of the system. Under this circumstance, the conventional signal detection circuit may be too slow in detecting the high speed inputted signal. More specifically, the signal detection circuit may be unable to determine if the inputted signal is the real signal or just noise that has emerged from the cable. If the signal detection circuit does not precisely awake the receiver when the real signal is transmitted to the receiver, the receiver may miss the inputted signal. To solve this problem, complex signal detection circuits using analog peak-bottom holders are developed. Under high operation speed requirement, however, the signal detection circuits are power-consumed with large level variation. That is, conventional signal detection circuits cannot look after both accuracy and simplicity. Therefore, providing an efficient and high speed signal detection circuit to precisely detect the real input signal is a significant concern in the field of signal transmission systems.